Sebaceous cyst
1258603
225535001
2008-07-14T05:04:32Z
70.249.40.138
{{Infobox_Disease
| Name = {{PAGENAME}}
| Image =
| Caption =
| DiseasesDB = 29388
| ICD10 = {{ICD10|L|72|1|l|60}}
| ICD9 = {{ICD9|706.2}}
| ICDO =
| OMIM =
| MedlinePlus = 000842
| eMedicineSubj =
| eMedicineTopic =
| MeshID = D004814
}}
[[Image:Sebaceous_cyst.jpg|thumb|right|Close-up of an infected sebaceous cyst that has abscessed, located behind the ear lobe.]]
[[Image:Sebaceous Cyst on ear.jpg|thumb|right|A small sebaceous cyst, located in the front of the ear lobe.]]
A '''sebaceous cyst''' (a form of '''[[trichilemmal]] [[cyst]]''') is a closed sac or [[cyst]] below the surface of the skin that has a lining that resembles the uppermost part ([[infundibulum]]) of a [[hair follicle]] and fills with a fatty white, semi-solid material called [[sebum]]. Sebum is produced by [[sebaceous glands]] of the [[Epidermis (skin)|epidermis]].
==Terminology==
It is sometimes (but not always) considered to be equivalent to [[epidermoid cyst]], or similar enough to be addressed as a single entity.<ref>{{cite web |url=http://www.mayoclinic.com/health/sebaceous-cysts/DS00979/DSECTION=3 |title=Sebaceous cysts: Causes - MayoClinic.com |accessdate=2007-11-14 |format= |work=}}</ref>
Some sources state that a "sebaceous cyst" is defined not by the contents of the cyst (sebum) but by the origin ([[sebaceous glands]]). Because an "epidermoid cyst" originates in the [[Epidermis (skin)|epidermis]], and a "pilar cyst" originates from [[hair follicles]], neither type of cyst would be considered a sebaceous cyst by this definition.<ref>{{cite web |url=http://www.patient.co.uk/showdoc/23068818/ |title=Epidermoid and Pilar Cysts Sometimes Called Sebaceous Cysts - Patient UK |accessdate=2007-11-14 |format= |work=}}</ref> However, in practice, the terms are often used interchangeably.
"True" sebaceous cysts are relatively rare.<ref>{{cite web |url=http://www.bad.org.uk/patients/leaflets/cysts.asp |title=cysts - British Association of Dermatologists |accessdate=2007-11-14 |format= |work=}}</ref>
==Presentation==
The [[scalp]], [[ear]]s, [[back]], [[face]], and [[upper arm]], are common sites for sebaceous cysts, though they may occur anywhere on the body except the palms of the [[hand]]s and [[sole]]s of the feet. In males a common place for them to develop is the [[scrotum]] and [[chest]] .They are more common in hairier areas, where in cases of long duration they could result in [[hair loss]] on the skin surface immediately above the cyst. They are smooth to the touch, vary in size, and are generally round in shape.
They are generally mobile masses that can consist of:
* [[fibrous tissues]] and fluids
* a fatty, ([[keratinous]]), substance that resembles [[cottage cheese]], in which case the cyst may be called "keratin cyst"
* a somewhat viscous, serosanguineous fluid (containing [[purulent]] and bloody material)
The nature of the contents of a sebaceous cyst, and of its surrounding capsule, will be determined by whether the cyst has ever been infected.
With surgery, a cyst can usually be excised in its entirety; poor surgical technique or previous infection leading to scarring and tethering of the cyst to the surrounding tissue may lead to rupture during excision and removal. A completely removed cyst will not recur, though if the patient has a predisposition to cyst formation, further cysts may develop in the same general area.
==Causes==
Blocked [[sebaceous gland]]s, swollen [[hair follicle]]s,<ref>{{cite web |url=http://www.nlm.nih.gov/medlineplus/ency/article/000842.htm |title=MedlinePlus Medical Encyclopedia: Sebaceous cyst |accessdate=2007-11-14 |format= |work=}}</ref> excessive [[testosterone]] production, will cause such cysts.<ref>{{cite web |url=http://www.aafp.org/afp/20020401/1409.html |title=Minimal Excision Technique for Epidermoid (Sebaceous) Cysts - April 1, 2002 - American Family Physician |accessdate=2007-10-26 |format= |work=}}</ref>
A case has been reported of sebaceous cyst being caused by [[Dermatobia hominis]].<ref name="pmid12354816">{{cite journal |author=Harbin LJ, Khan M, Thompson EM, Goldin RD |title=A sebaceous cyst with a difference: Dermatobia hominis |journal=J. Clin. Pathol. |volume=55 |issue=10 |pages=798–9 |year=2002 |pmid=12354816 |doi=}}</ref>
==Treatment==
{{Refimprovesect|date=September 2007}}
Sebaceous cysts generally do not require medical treatment. However, if they continue to grow, they may become unsightly, painful, infected, or all of the above.
===Surgical===
[[surgery|Surgical]] [[excision]] of a sebaceous cyst is a simple procedure to completely remove the sac and its contents. <ref name="pmid2349906">{{cite journal |author=Klin B, Ashkenazi H |title=Sebaceous cyst excision with minimal surgery |journal=American family physician |volume=41 |issue=6 |pages=1746–8 |year=1990 |pmid=2349906 |doi=}}</ref>
There are three general approaches used: traditional wide excision, minimal excision, and punch biopsy excision.<ref name="pmid17403333">{{cite journal |author=Moore RB, Fagan EB, Hulkower S, Skolnik DC, O'Sullivan G |title=Clinical inquiries. What's the best treatment for sebaceous cysts? |journal=The Journal of family practice |volume=56 |issue=4 |pages=315–6 |year=2007 |pmid=17403333 |doi=}}</ref>
The typical outpatient surgical procedure for cyst removal is to numb the area around the cyst with a [[local anaesthetic]], then to use a [[scalpel]] to open the lesion with either a single cut down the center of the swelling, or an oval cut on both sides of the centerpoint. If the cyst is small, it may be [[lanced]] instead. The person performing the surgery will squeeze out the [[keratin]] (the semi-solid material consisting principally of sebum and dead skin cells) surrounding the cyst, then use blunt-headed scissors or another instrument to hold the incision wide open while using fingers or forceps to try to remove the cyst intact. If the cyst can be removed in one piece, the "cure rate" is 100%.{{Fact|date=November 2007}} If, however, it is fragmented and cannot be entirely recovered, the operator may use [[curettage]] (scraping) to remove the remaining exposed fragments, then burn them with an electro-[[cauterization]] tool, in an effort to destroy them in place. In such cases the cyst may or may not recur. In either case, the incision is then [[disinfected]] and, if necessary, the skin is stitched back together over it. A [[scar]] will most likely result.
In some cases where "cure rate" is not 100% the resulting hole is filled with an antiseptic ribbon after washing it with an iodine based solution. This is then covered with a field dressing. The ribbon and the dressing are to be changed once or twice daily for 7-10 days after which the incision is sewed up.
An infected cyst may require oral [[antibiotic]]s or other treatment before and/or after excision.
An approach involving [[incision]], rather than excision, has also been proposed.<ref name="pmid11322399">{{cite journal |author=Nakamura M |title=Treating a sebaceous cyst: an incisional technique |journal=Aesthetic plastic surgery |volume=25 |issue=1 |pages=52–6 |year=2001 |pmid=11322399 |doi=}}</ref>
===Nonsurgical===
Another common and effective method of treatment involves placement of a [[heat-pad]] directly on the cyst for about fifteen minutes, twice daily, for about 10 days (depending on size and location of the cyst).<ref>{{cite web |url=http://health.yahoo.com/ency/healthwise/tw6860 |title=Home treatment for a sebaceous cyst - Yahoo! Health |accessdate=2007-11-14 |format= |work=}}</ref>
This method works by bringing the temperature of the wax-like material inside of the cyst to a temperature at which it melts, and can be reabsorbed and processed by the body, as a small amount of oily fluid. This method is preferred over surgery both for reasons of associated costs and risks of surgery. This methodology is not applicable for non-sebaceous cysts, however, as other varieties of cysts do not contain the same hardened sebum deposits, and therefore do not melt to be reabsorbed by the body.
Under no circumstances must one try to pop the cyst, as it can lead to infection of the surrounding tissue. The neck is a particularly dangerous region, due to the glands and blood vessels.
==References==
{{reflist|2}}
==External links==
* [http://www.aafp.org/afp/20020401/1409.html Minimal Excision Technique for Epidermoid (Sebaceous) Cysts] at [[American Family Physician]]
* [http://www.umm.edu/dermatology-info/cysts.htm Overview] at [[University of Maryland]]
* [http://www.emedicine.com/derm/topic860.htm (article "Epidermal Inclusion Cyst")] at [[eMedicine]]
{{Diseases of the skin and subcutaneous tissue}}
[[Category:Dermatology]]
[[de:Atherom]]
[[it:Cisti sebacea]]
[[pl:Kaszak]]
[[pt:Cisto sebáceo]]